Process for transalkylation and preparation of higher fatty acids from magnesium lower alkyl compounds



. dihexyl.

United States Patent 3,217,020 PROCESS FOR TRANSALKYLATION AND PREPA- RATION OF HIGHER FATTY ACIDS FROM MAGNESIUM LOWER ALKYL COMPOUNDS Karl Ziegler, Kaiser Wilhelm Platz 1, Mulheim (Ruhr), Germany, and Roland Koster and Wolfram Grimme, Mulheim (Ruhr), Germany; said Koster and said Grimme assignors to said Ziegler No Drawing. Filed Feb. 21, 1961, Ser. No. 90,641 Claims priority, application Germany, Feb. 25, 1960, Z 7,837; Aug. 13, 1960, Z 8,203 12 Claims. (Cl. 260-413) This invention is concerned with the transalkylation of magnesium alkyl compounds.

Lower magnesium dialkyls, in particular magnesium diethyl and/or dipropyl, can readily be obtained by new electrolytic processes using complex alkali metal aluminum alkyls as electrolytes, as described for example in patent applications Nos. 548,862 (now Patent 2,985,568), 27,220 (now abandoned) and 27,218 (now abandoned). If an attempt is made to use these electrolytic processes for the production of magnesium alkyls the alkyl radicals of which contain a higher number of carbon atoms the difliculty is encountered that the conductivity of the liquid electrolyte continuously falls with increase in the size of the alkyl radicals which are introduced. It has been found for practical purposes that the electrolytic process is of hardly no interest for compounds with larger alkyl radicals than occur in magnesium dipentyl and magnesium The electrolytic synthesis of magnesium diethyl and magnesium dipropyl is undoubtedly the most successful.

The production of magnesium dialkyls of higher carbon number is in fact a problem which has still not been satisfactorily solved technically. Of the organomagnesium compounds only the halogen magnesium Grignard compounds are known in any number and with a large number of carbon atoms, and for the production of these compounds it is necessary to use organic halogen compounds.

The relationship is completely reversed with organic aluminum compounds. In this case, the substances which are analogous to the Grignard compounds, namely R Alhalogen and RAl (halogenh, can only be prepared directly from aluminum and halogen alkyls when R:CH and C H it being otherwise necessary to work with the alkyl iodides, which generally is not economical. The

higher homologues can only be obtained by treating aluminum trialkyls with aluminum chloride or bromide. On the other hand, the higher aluminum trialkyls can easily be prepared from the corresponding olefines, aluminum and hydrogen. It is also possible to make use of the process which is very specific as to the aluminum trialkyls and which consists in treating low aluminum trialkyls with the simplest olefine, namely ethylene, so that long or comparatively short hydrocarbon chains are formed on the aluminum, depending on the quantity of ethylene which is used in accordance with the following equation:

A1R3 2 4) 11R] 3 An analogous synthesis reaction which proceeds smoothly in a similar manner is unknown for magnesium alkyls. It is true that they react with ethylene, but it is always predominantly polyethylene which is formed, there being no formation of reaction products comparable with the synthesis products of limited carbon number which are formed with aluminum trialkyls.

The present invention is concerned with a process for the transalkylation of magnesium alkyl compounds, in particular for the production of magnesium alkyl compounds of relatively high carbon number from those having a lower carbon number, in which the higher alkyl 3,217,020 Patented Nov. 9, 1965 radicals may originate from lower olefines. The process according to the invention thus makes it possible for olefines to be employed for the synthesis of magnesium alkyl compounds in particular of high carbon number in a manner which was only hitherto possible with the aluminum alkyl compounds.

Since the magnesium alkyls are greatly superior to the aluminum alkyls as regards reactivity in many respects, for example, with respect to carbon dioxide, the invention provides an important technical advance in organometallic synthesis. It is known that carbon dioxide reacts directly with only a single AlC bond in aluminum trialkyls, so that aluminum trialkyls can only be transformed with carbon dioxide into carboxylic acids under gentle conditions in a yield which is at most only 33%, based on all the alkyl groups.

If the reaction of the aluminum compounds with carbon dioxide takes place under pressure and at high temperature, it is possible to cause a second AlC bond to react. However, such a maximum yield of 66% cannot be exceeded in the synthesis of carboxylic acid. As will later be shown, it has on the contrary surprisingly been found that both the MgC bonds in the magnesium dialkyl compounds, in particular saturated magnesium dialkyls, react extremely easily with carbon dioxide. As regards organic magnesium compounds of the Grignard compound type, reaction with carbon dioxide to carboxylic acids and other reaction products is known. However, it has now been found that not only with these organic magnesium compounds can carboxylic acids be prepared, but that the synthesis of carboxylic acid by this method can be applied with advantage to magnesium dialkyls with saturated alkyl radicals. Almost quantitative yields of carboxylic acids may readily be obtained by treating magnesium dialkyls with carbon dioxide. On account of their high reactivity, the magnesium alkyl compounds obtained according to the invention are however also valuable for a number of other reactions. For example, the use of magnesium dialkyls offers important advantages as compared with the use of aluminum alkyls for autoxidation with formation of alcohols. The reactions occur more easily with the organic magnesium compounds and are completed in a shorter time.

The subject of the present invention is a process for the transalkylation of magnesium alkyl compounds, in which organic magnesium compounds are reacted with boron alkyl compounds. In this process, it is advantageous to use free boron trialkyls as one of the components of the reaction mixture.

According to one feature of the invention magnesium dialkyl compounds are employed as magnesium alkyl compounds. Preferably magnesium dialkyl compounds with lower alkyl radicals, that is radicals containing up to 6 and preferably 2 to 3 carbon atoms are reacted with free boron trialkyls having higher alkyl radicals. However, the process according to the invention is not restricted to the use of magnesium dialkyl compounds as organic magnesium compounds as these can be replaced by other compounds, for example, the known Grignard compounds. As is known, these Grignard compounds have only one MgC- bond. The reactions which take place in the process according to the invention will hereinafter he explained for convenience with reference to the magnesium dialkyls only, but it is to be understood that these reactions are also applicable to the Grignard compounds.

If the magnesium alkyls and boron alkyls are reacted according to the invention an equilibrium is set up as shown in the following equation provided that the alkyl radicals were initially different in the two reactants:

This equation represents in somewhat simplified form what actually takes place in practice as the reaction mixture does not contain only the homogeneous magnesium dialkyls MgR and MgR and the two homogeneous boron trialkyls BR and BR but also possibly mixed types of compounds, such as MgRR, BRR and BR R'. If lower organoalkyl radicals are now introduced with the magnesium dialkyl in accordance with the process of the invention into such a mixture (R in this case being the radical of lower carbon number), the compound BR is the component with the lowest boiling point. In yet another particularly preferred embodiment of the invention, the component BR with the lowest boiling point is removed from the reaction mixture. By this means, there is necessarily formed a residue containing almost exclusively MgR i.e. the magnesium dialkyl compound with the highest alkyl radical derived from the boron compound introduced into the reaction mixture. The most favourable results are obtained in the process according to the invention by using magnesium diethyl and magnesium dipropyl, although higher homologues thereof up to about magnesium dihexyl can also be satisfactorily used for this embodiment of the invention. Establishment of the exchange equilibria proceeds very quickly. It is sufficient for this purpose for the reaction components to be stirred together at room temperature. One may, if desired, also carry out the process in the presence of a solvent or suspending agent. Preferably the process is carried out at an elevated temperature, for example by heating the reaction components to temperatures of approximately between room temperature and 140 C. Preferably the upper temperature limit of 140 should not be substantially exceeded as above this temperature the magnesium dialkyls do in fact become unstable and split up into relatively small fractions, for example magnesium hydride and olefine. In other respects, however, the invention is not limited in any way as regards temperature for the adjustment of the exchange equilibria.

'The volatile boron alkyl compounds which form in the reaction can be removed in various Ways from the reaction mixture in accordance with the invention. For example, the reaction mixture can be directly heated to a maximum of about 140 C. By carrying out the proc' ess in this manner the boron triethyl (B.P. 95 C.) which forms, distills off. This distillation is facilitated by working under reduced pressure, which reduced pressure may be utilized, if desired, at the time of removing the boron triethyl. It is then only necessary to heat the reaction mixture to the temperature required for removing the last fractions of boron triethyl. If higher boron alkyl compounds are to be removed from the reaction mixture, it is generally preferable to work under more or less greatly reduced pressure.

The removal of the volatile boron alkyl compounds from the reaction mixture is substantially facilitated if a so-called entraining agent is used. This entraining agent is preferably a solvent of suitable boiling point. In this embodiment of the invention, it is again possible to proceed in various ways. Thus one may employ an entraining agent the boiling point of which is suitably higher than the boron alkyl compound to be removed. The starting mixture containing the entraining agent is then distilled, for example using a column. The column retains the entraining agent and substantially permits only the boron alkyl of lower boiling point to distill over. Suitable entraining agents for boron triethyl are for example toluene, xylene, octane or isooctane. This process may be effected in the presence of ethers, and ethers which can be used according to the invention are for example dipropyl ether or di-n-butyl ether. After distilling off the boron trialkyl, solutions of the magnesium dialkyl in the corresponding ether are then obtained. The higher magnesium dialkyls are also soluble in hydrocarbons, in particular aromatic hydrocarbons. It may also be advisable with this form of the invention to operate under reduced pressure. Even in this case, the separation of the mixtures of magnesium and boron alkyl compounds is facilitated by this means. The use of reduced pressures will again be particularly advisable if it is desired to remove boron alkyls of relatively high boiling point, for example higher than about C., and/or if it is particularly desired to protect the magnesium compounds.

When using an entraining agent, it may however also be desirable according to the invention to use those entraining agents with a boiling point which substantially corresponds to that of the boron alkyl compound to be removed. In this embodiment of the invention, the boron alkyl compounds are then removed together with the entraining agent from the reaction mixture. The magnesium dialkyls of higher boiling point formed by the reaction are then left behind as a pure distillation residue. The mixture which is distilled off and which consists of entraining agent and boron alkyl compound can either be further employed as such or can be separated in many different ways, for example by chemical reaction of the boron alkyl compounds. One particularly economical form of separation which can be carried out continuously and also by a cyclic process is as follows: a supply of entraining agent, for example benzene, admixed with finely suspended sodium hydride, is allowed to boil in an evaporator vessel. The benzene vapours are conducted through the reaction mixture containing magnesium and boron alkyl compounds, whereas the condensate forming from this mixture is returned into the evaporation vessel for the benzene, the said vessel containing sodium hydride. In this vessel, the boron alkyl contained in the condensate is immediately combined with the sodium hydride and the vapours which now reach the reaction mixture from the evaporation vessel always consist of the pure entraining agent in vapour form. It is possible in this way, using a limited quantity of the entraining agent, for boron alkyl compounds to be removed in practically any desired quantities from the mixture with the magnesium alkyl com.- pounds.

It is thus possible according to the invention to effect the process in a cyclic manner until no more boron alkyl is detectable in the condensate. The boron alkyl is then present in the evaporator vessel with the entraining agent, for example, benzene, as a non-volatile sodium-boron trialkyl hydride (for example sodium triethyl borohydride). By adopting this procedure it is thus possible in practice, in a single working step, for the mixtures of substances introduced to be completely separated in a gentle manner. The alkali metal boron trialkyl hydride which forms is an industrially important compound and can be further utilized as such.

As already explained, the transalkylation of magnesium alkyls according to the invention is especially important for use in connection with mixtures of substances formed by electrolysis of organometallic compounds. It is in this connection that the possibility of separation just described has other important advantages. In patent application No. 69,275, filed November 15, 1960, now Patent No. 3,163,679, there is described a method by which sodium boron triethyl hydride can easily be converted by addition of ethylene into sodium-boron tetraethyl. This so dium-boron tetraethyl is suitable as electrolyte component for the electrolytic production of magnesium diethyl. In such a case, the readily separable boron triethyl is formed, so that it is possible with this embodiment of the invention for the separation of the reaction mixture transalkylated after the electrolysis to be combined with advantage with the working steps of the electrolysis itself. As further explained hereinafter, it is possible with one particularly preferred embodiment of the invention for the low-boiling boron trialkyl separated from the trans alkylation mixture, for example the boron triethyl, to be reconverted into higher boron trialkyls and thus into the starting materials for the transalkylation according to the invention. By this means, it is then possible according to the invention to use closed cyclic processes which comprise the transalkylation according to the invention. This ensures maximum industrial economy of the invention.

The embodiments of the invention as so far described for separating the transalkylation mixture all operate on the principle of removing the most volatile component from the reaction mixture. In another and likewise very important embodiment of the invention, it is however, also possible to use an entirely different method of procedure. The reaction between magnesium alkyls and boron alkyls has been formulated above as an equilibrium reaction. According to the rule of mass action, the position of any equilibrium can be influenced by the use of the excess of one component. Consequently, when a particular magnesium compound, such as a magnesium dipropyl, is treated with an excess of another boron alkyl, such as boron trioctyl, a major proportion of the magnesium is combined with octyl a short time after mixing. Accordingly, the total propyl will be largely attached to the boron. There is a very large difference between magnesium and boron alkyls as regards their respective reactivity. For example, the magnesium alkyls react very easily with carbon dioxide, Whereas boron alkyls do not react at all. Consequently, if such mixtures of magnesium alkyls in particular magnesium dialkyls, and an excess of higher boron trialkyls are treated with carbon dioxide, the magnesium salts of the higher carboxylic acids are preferentially formed. These can be easily separated in the usual manner from the excess of the higher boron alkyl compound and the lower boron alkyl. The lower boron alkyl can moreover be easily separated from the higher boron alkyl by distillation and the unreacted higher boron alkyl can for example be used again in the reaction with magnesium dialkyl. In this form of the invention, any heating of magnesium dialkyls is avoided. The separation processes only take place with substances which are substantially stable to heat.

It was not to be anticipated that the transalkylation according to the invention could be carried out without any difiiculty in only short reaction times and at normal pressure or only slightly lowered pressure. Rather was it to be expected that the boron alkyls, together with the magnesium alkyls, would form complex compounds of higher stability. The parent substance of such possible complex compounds, namely magnesium borohyd'ride, Mg(BH is known as a quite stable substance which does not differ substantially from the alkali metal borohydrides as regards its properties. Accordingly, with the mixing of magnesium and boron alkyls, it was to be expected that similarly stable complex compounds would be formed, such as are the alkali metal boron tetraalkyl-s. These cannot be split into alkali metal alkyls and boron trialkyls. However, in actual fact and, not as anticipated, it seems to be that the magnesium alkyl-boron trialkyl complex compounds do not exist or have only a very low stability. Another possible reason for the good progress of the process according to the invention is the comparatively high volatility of the lower boron trialkyls. This point of view is however of subordinate importance as compared with the complex stability.

The boron trialkyls necessary for carrying out the in vention can be obtained 'by various known methods, which ultimately in general commence with olefines. They can for example be obtained from trialkyl boraZanes or from diborane which today is manufactured on an industrial scale by the use of olefines or from other boron trialkyls, more especially boron triisobutyl, by displacement of the alkyl radicals, for example of isobutylene by other olefines. Boron triisobutyl is readily obtainable from aluminum triisobutyl and boron fluoride, boric acid ester or with boroxoles. Higher boron alkyls which have been prepared by the process of patent application No. 786,032 (now Patent 2,975,216) from lower boron alkyls with ethylene can be used with particular advantage according to the invention. According. to this process, the synthesis reaction known in connection with aluminum trialkyls can be transferred to the boron trialkyls when working in the presence of small catalytic quantities of true aluminum trialkyls.

In this case, the lower boron trialkyls separated out from the transalkylation mixtures by the methods possible according to the invention which have been described can be used as starting material for the reaction with ethylene. This makes it possible to use cyclic processes, with which the different boron alkyl compounds are conducted in circulation through the separate processing stages, and by means of such processes, the ethylene or its polymers can be transferred to the magnesium compounds. With such a combination process, i.e. with the combination of the production of higher boron trialkyls from lower boron alkyls by addition of ethylene with the process according to the invention, higher magnesium alkyl compounds of a certain statistical range of variation in the length of the alkyl groups are obtainable in an extremely simple manner from ethylene.

As already mentioned, the magnesium dialkyl compounds can also be replaced according to the invention by the Grignard compounds containing only one MgC bond. This procedure can also be of technical importance, especially if it is for example desired that any relatively valuable olefine of complicated structure should be converted in its double bond, for example into a saturated carboxylic acid with one more carbon atoms or even if for example conversions in the range of molecular size of C and above for example of C and higher, are to be carried out. It is possible in this way to enter the field of the synthetic waxes. In this case, the starting materials are aliphatic Grignard compounds, i.e. alkylmagnesium halides.

The conversion already mentioned of the magnesium dialkyl compounds with carbon dioxide proceeds in a surprisingly complete manner according to the invention and leads to practically quantitative conversions to the carboxylic acids. The chemical behavior of these magnesium dialkyls is little known by comparison with the very extensive data existing in respect of the Grignard compounds. From the few literature references concerning these compounds, it was to be expected that the magnesium dialkyls have a higher reactivity than the Grignard compounds. The few works which are concerned with the reaction between magnesium dialkyls and carbon dioxide describe the reaction between unsaturated magnesium dialkyl compounds and CO It was found in this connection that these unsaturated organic magnesium compounds are highly reactive, so that only a small proportion of carboxylic acids (the first reaction product between organic magnesium compound and CO is obtained. It is for example known that with the reaction of dibutenyl magnesium and CO the corresponding carboxylic acid is obtained with a yield of only 37%. The few other known reactions in this field show that in this case the yield of carboxylic acid can be even lower and even values of only 5% of carboxylic acid are indicated.

Nothing has so far become known concerning the chemical behavior of dialkyl magnesium compounds with saturated alkyl radicals in the reaction with carbon dioxide. However, if these saturated magnesium dialkyls are treated with carbon dioxide, the carboxylic acid magnesium salts are formed easily and in a practically quantitative conversion. These magnesium salts can in a manner known per se be transformed into free carboxylic acids. This is for example effected in the usual manner by decomposition with acids. Decomposition with 10% to 25% sulphuric acid is for example suitable for this purpose.

Solid carbon dioxide can be used for the carboxylation of the magnesium dialkyls. It is for example, possible to add the magnesium dialkyls to the solid carbon dioxide. It is however more suitable to work in the presence of a solvent, which naturally must be neutral to the reaction. Examples of such solvents are dry ether, isooctane or toluene.

The carboxylic acids are then obtained in this solvent and they can be recovered therefrom by usual measures, such as for example by extraction with alkali and subsequent decomposition of the alkali metal salts.

Taking into account the prior knowledge concerning the chemical behavior of magnesium dialkyl compounds, it has thus surprisingly been found that the saturated magnesium dialkyls are not only highly reactive with respect to carbon dioxide, but that in this way the carboxylic acids or magnesium salts of such acids are, in general, always obtained with very high yields which frequently are practically quantitative. It is especially surprising in this connection that not only individual magnesium dialkyl compounds show this strong tendency to form carboxylic acids, but that the specific carboxylic acid formation is inherent in the entire class of compounds, as can be proved by the reaction of saturated magnesium dialkyl compounds with alkyl radicals having a carbon number of up to 30.

In order that the invention may be further understood the following examples are given by way of illustration only:

Example 1 73 g. (0.434 mol) of dodecene-(l) are heated to 150 C. in a three-necked flask comprising a dropping funnel, stirrer device and distillation head and 16.0 g. (0.14 mol) of triethyl borazane are added dropwise while stirring. Triethylamine immediately distills 01f. A residue is extracted at 10 mm. Hg. 17.8 g.(0.217 mol) of magnesium diethyl is then dissolved at room temperature with stirring in the boron tridodecyl which is formed. The solution is heated in a bath under reduced pressure (10 mm. Hg) to 50 C., 13.5 g. of boron triethyl distilling off.

82 g. of magnesium didodecyl remain as a crystal-clear viscous oil with the correct magnesium content (6.6%). The presence of magnesium didodecyl was proved as follows: 18.1 g. of the substance are dissolved in the absence of air in 100 cc. of dry. and air-free ether and this mixture is poured on to about 20 to 30 g. of solid carbon dioxide, again with exclusion of air. After complete evaporation of the carbon dioxide, the reaction mixture is decomposed with 10% sulphuric acid, the ether layer is extracted with caustic alkali solution and the carboxylic acid which has formed is recovered in the usual way from the soap solution. 19 g. (89% of the theoretical) of tridecyl acid with the melting point 41 C. are obtained.

Example 2 35 g. of boric acid trimethyl ester are added to 118 g. of aluminum trialkyl, prepared in known manner from 1-vinyl-3-cyclohexene and aluminum triisobutyl, in the absence of air and after the reaction, which gives rise to violent spontaneous heating, has subsided, the substance is heated for another 2 hours to 100 C. The reaction mixture is then carefully introduced in the absence of air into 250 cc. of 5% sulphuric acid+250 g. of finely crushed ice, the oil which precipitates is separated out as quickly as possible, it is washed with iced water and cold bicarbonate solution and finally dried (always in the absence of air) over anhydrous calcium chloride.

The boron tri-fi-[cyclohex-3-ene-1-yl] ethyl finally obtained in this way is dissolved in 300 cc. of dry and anhydrous toluene, 41 g. of magnesium diethyl are added (always in the absence of air), the mixture is heated under a small column and the temperature is so adjusted that boron triethyl preferentially distills over between 90 C. and approximately 105 C. The magnesium diethyl dissolves. The experiment is completed when no more boron triethyl appears in the distillate. If necessary, toluene is also added during the distillation.

8 If the toluene is now extracted in vacuo, a magnesium compound of the formula:

is left behind as a thick colorless oil with a magnesium content 9.9%.

If a sample is carboxylated as described in Example 1 (or even directly in the original toluene solution), the fl-[l-cyclohexen 3 yl] propionic acid (melting point 33 C.) is obtained with a yield higher than of the theoretical.

Example 3 73 g. (0.89 mol) of magnesium diethyl are dissolved in 185.1 g. of a statistical boron trialkyl mixture with a boron content of 3.5% by weight (prepared according to patent application 786,032 (now Patent 2,975,215) from boron triethyl and ethylene with aluminum triethyl as catalyst), by stirring for 1 hours at 80 C. 58 g. of boron triethyl are distilled off from the reaction mixture at 80 C./ 10 mm. Hg. The residue consists of a clear viscous oil with the magnesium content of 10.9%.

In order to identify the magnesium dialkyl which forms, the residue is dissolved in 0.5 liter of ether and added to solid carbon dioxide. The magnesium salts of the fatty acids are decomposed with cc. of 25% sulphuric acid and the aqueous phase is extracted twice with ether. The ether is evaporated off from the combined ether extracts and the residue is taken up in methanolic caustic potash solution. Paraffinic constituents are separated out with pentane and the methanolic solution is concentrated. After acidification with concentrated hydrochloric acid, the fatty acids are precipitiated; they are washed with a little water and fractionated on a quartz rotating band column. The following fatty acids are Example 4 In a manner analogous to that of the foregoing example 133.7 g. of a statistical mixture of boron trialkyls, B[(C H -n-C H (synthesized from boron tripropyl), with a boron content of 4.85% by weight (0.601 mol) are reacted with 74.5 g. (0.903 mol) of magnesium diethyl. The result is a viscous oil with a magnesium content of 14.5% by weight. This magnesium dialkyl mixture was again identified by carboxylation:

Acid Boiling point Yield,

Butyric acid 51 Caproic acid 72 Caprylic acid 40 Capric acid 16 Laurie acid- 5 Example 5 92.5 g. of l-docosene (0.3 mol) with the melting point 41 C. are dissolved in 350 ml. of anhydrous and air-free diethyl ether. Diborane is introduced into this solution at room temperature until saturation is reached. After 9 distilling ofi the ether, the formed boron tridocosyl is left as a colorless viscous liquid (94 g. boron content 1.15%

The boron alkyl is dissolved in 350 ml. of dry perhydrocumene and 16.5 g. of magnesium di-n-propyl are added. The reaction mixture is heated to 70 C. and the solvent is distilled ofi together with boron tripropyl formed at a pressure of mm. Hg. Magnesium didocosyl is left as a colorless viscous residue (97 g., magnesium content: 3.7%).

Magnesium didocosyl (32 g.) is dissolved in dry ether and carboxylated With solid carbon dioxide. The tricosanic acid which is formed is worked up and purified by known process. Yield: 31 g., corresponding to 88% of the theoretical, melting point 80 to 81 C.

Example 6 112 g. (4 mols) of ethylene are forced in under pressure into a 1 liter autoclave containing 171 g. of boron tri-n-octadecyl (0.22 mol) and 5 g. of aluminum tri-noctadecyl. At a temperature of 140 C., the pressure in the autoclave quickly falls and has practically disappeared after 2 hours. After cooling, 1.0 g. of boron trifluoride diethyletherate is added to the mixture and the autoclave is shaken for another hour at 140 C. The statistical mixture of boron alkyls thus obtained in accordance with patent application 786,032 (now Patent 2,975,215) has a boron content of 0.85%, corresponding on average to B 3u s1)3- The boron trialkyl mixture is dissolved in 1 liter of isooctane and added to 27.5 g. of magnesium diethyl. The reaction mixture is heated to 80 C. and the solvent is completely distilled off together with boron triethyl (17 g.) at 500 mm. Hg. The magnesium diethyl is thus dissolved. 5.3 g. of sodium hydride, suspended in 50 cc. of isooctane, are added to the distillate and the mixture is heated for 1 hour to boiling While stirring (with exclusion of air). The isooctane is then distilled off except for a residue of about 50 cc. The distillate is added again to the original distillation residue and the operation is repeated. After the second such distillation, or in any case after the third, no more boron alkyl escapes. The distillates from the repetitions are in each case added to the same, already used sodium hydride. Finally, the statistical mixture of higher magnesium alkyls remains as a colorless waxy residue (300 g.).

In order further to characterise them the higher magnesium alkyls are dissolved in the recovered isooctane and solid carbon dioxide is added thereto. The carboxylic acids which are formed are isolated by known processes. Yield: 275 g., corresponding to 87% of the theoretical. Neutralization factor: 120, corresponding to the average molecular Weight of 466.

Oxygen determination: 0.69% 0.

Example 7 30 g. (0.086 mol) of boron tri-n-octyl are added to 0.25 mol of ethyl magnesium bromide, dissolved in about 150 cc. of diethyl ether under nitrogen and at room temperature, the temperature rising to about 35 C. The boron triethyl so formed (8 g.) is then distilled off together with the solvent. Finally, the n-octyl magnesium bromide is precipitated. If a sample is carboxylated, as described in Example 1, pelargonic acid with a melting point of 11 to 12 C. is obtained in a yield of more than 80% of the theoretical.

Example 8 5 g. of diborane are introduced into a solution of 112 g. (1 mol) of 2,4,4-tn'methyl-1-pentene in 500 cc. of ethylene glycol diethyl ether with stirring, at room temperature. A Grignard solution consisting of 26 g. of magnesium and 120 g. of ethyl bromide in 350 cc. of ethylene glycol diethyl ether is then added thereto. First of all, 31 g. of boron triethyl (B.P. =39 C.) and 10 then a about 25 g. of ethylene glycol diethyl ether (B.P. =70 C.) are distilled off through a column at 100 mm. Hg. There is thus obtained a solution of H which can be used for various further reactions in the same way as a Grignard solution prepared from the corresponding alkyl halide. This can, for example be shown in the following manner: the reaction mixture is deposited on solid carbon dioxide and stirred until room temperature is reached. Decomposition is effected with dilute sulphuric acid and the carboxylic acid which has formed is isolated in known manner. 136 g. of 3,5,5- trimethyl caproic acid are recovered. B.P. =103104 C.

Example 9 250 cc. of a normal molar solution of ethyl magnesium chloride in ethylene glycol diethyl ether are added to 70 g. (0.2 mol) of boron tri-Z-ethyl-hexyl in a nitrogen atmosphere. At 100 mm. Hg, 17 g. of boron triethyl and about 10 g. of ethylene glycol diethyl ether are obtained by fractional distillation. In order to show that has been formed, it is possible to proceed as indicated in Example 8. 76 g. of li-ethyl enanthic acid are obtained, with a boiling point 715 C./0.1 mm. Hg.

Example 10 32 g. of N-triethyl borazane are added under nitrogen to 213 g. (0.8 mol) of l-nonadecene and are heated under slightly reduced pressure to 100-150 C. until no more triethyl amine distills over into a highly cooled receiver connected before the vessel. The boron tri-nonadecyl which is formed is then introduced into a solution of 20. g. of magnesium and 80 g. of bromomethyl in 500 cc. of ether, the solution being at a temperature of 20 C. The reaction mixture is then brought to room temperature with stirring. Boron trimethyl thereby escapes and this is conducted in a stream of nitrogen through a Washing bottle and is absorbed therein by being combined with pyridine. After the evolution of gas has subsided, the reaction mixture is heated for 1 hour under reflux. 14 g. of boron trimethyl as pyridine adduct are collected during the reaction. The solution of nonodecyl magnesium bromide which is obtained can be used as any Grignard solution for introducing nonadecyl radicals into other compounds. The reaction with CO can again be used for proving the formation thereof. By conversion with solid carbon dioxide, 225 g. of nonadecane carboxylic acid can be obtained from the mixture. Melting point of the acid after recrystallisation from ethanol, is 75 C. and of the amide 108 C.

Example 11 1.4 liters of a 1.62-molar solution of methyl magnesium iodide in ether are added to 276 g. (0.75 mol) of boron tri-2-phenyl propyl under nitrogen at 20 C. The reaction mixture is brought to room temperature while stirring. Boron trimethyl escapes and this is conducted in a stream of nitrogen from the reaction mixture and is collected in a Washing bottle with pyridine. After the evolution of gas has subsided, the reaction mixture is heated for 1 hour under reflux. During the reaction, 40 g. of boron trimethyl are collected as pyridine adduct. In order to prove the formation of the Grignard compound G6H5-C H- G H MgI it is again treated with solid carbon dioxide as in the pre- 1 1 ceding examples. Working up yields 330 g. of ,B-phenyl butyric acid with the B.P. of 168 to 169 C.

Example 12 A Grignard solution of 93 g. of n-butyl chloride and 24 g. of magnesium in 500 cc. of ether is introduced with vigorous stirring into 1 liter of boiling toluene, first ether and finally 200 cc. of toluene distilling off. The pasty mass thus formed is thereafter completely dried by further heating in vacuo to 100 C.

On the other hand, 256 g. of boron trioctadecyl, with addition of i g. of aluminum trioctadecyl, are treated under nitrogen in a shaker-type autoclave at 130 C. with ethylene at a pressure of 100 atm. until altogether 170- 180 g. of ethylene have been taken up. It is advisable also to add 1 liter of dry and air-free benzene to the autoclave before the reaction.

The total content of the autoclave is then admixed with the solid residue from the Gn'gnard solution, the benzene is distilled off and the mixture is then heated under high vacuum to 120 to 140 C., 50 to 60 g. of boron tri-n-butyl finally distilling over a period of several hours into a highly cooled receiver.

The remaining organic magnesium compound is preferably dissolved out with toluene under nitrogen. The solution is then carboxylated with CO and finally yields about 400 g. of a mixture of waxy acids of average composition C13H37(C2H4)6CO2H.

What we claim is:

1. A process for the production of higher carboxylic acids which comprises the steps of reacting a member selected from the group consisting of lower magnesium dialkyls and lower alkyl magnesium halides with a higher boron trialkyl at an elevated temperature of up to about 140 C. and at reduced pressure, removing the lower boron trialkyl which is formed from the reaction mixture by distillation, treating the distillation residue with carbon dioxide to form the magnesium salts of the corresponding carboxylic acids, reacting said salts with acid to thereby produce the free carboxylic acids and isolating the resulting higher carboxylic acids thus produced.

2. A process according to claim 1 in which the magnesium salts are reacted with sulphuric acid.

3. A process according to claim 2 wherein the magnesium salts are reacted with 10 to 25% aqueous sulphuric acid.

4. A process according to claim 1 wherein said carbon dioxide used is solid carbon dioxide.

5. A process for the transalkylation of magnesium alkyl compounds to produce higher magnesium alkyl compounds, in the form of their corresponding carboxylic acids which comprises the steps of reacting a member selected from the group consisting of lower magnesium dialkyls and lower alkyl magnesium halides at a temperature of up to about 140 C. and at reduced pressure with higher boron trialkyl, separating the lower boron trialkyl which is formed from the reaction mixture by distillation in the presence of an entraining agent, the boiling point of which is substantially the same as that of the boron trialkyl formed, supplying the entraining agent from a supply vessel which also contains an alkali metal hydride introducing the distillate from the distillation comprising entraining agent and lower boron trialkyl into the supply vessel so that the boron trialkyl is continuously removed from the reaction mixture in combined form, recycling the entraining agent back into the distillation, continuing the distillation until substantially all of the boron trialkyl has been distilled over,

reacting the distillation residue with carbon dioxide to form the magnesium salts of the corresponding carboxylic acids and reacting said salts with a mineral acid to thereby produce the free carboxylic acids.

6. A process for the transalkylation of magnesium alkyl compounds which comprises the steps of reacting a member selected from the group consisting of lower magnesium dialkyls, the alkyl radicals of which contain up to 6 carbon atoms and lower alkyl magnesium halides, the alkyl radicals of which contain from 2 to 6 carbon atoms, with a higher boron trialkyl, and separately recovering the transalkylation products thereby produced.

7. A process according to claim 6 which comprises efiecting said reaction at an elevated temperature.

8. A process for the transalkylation of magnesium alkyl compounds which comprises the steps of reacting a member selected from the group consisting of lower magnesium dialkyls and lower alkyl magnesium halides, with a higher boron trialkyl at an elevated temperature of up to about C. and at reduced pressure, separating the lower boron trialkyls which are formed by distillation and isolating the transalkylated alkyl magnesium compound from the distillation residue.

9. A process according to claim 8 which comprises effecting the distillation of the boron trialkyls in the presence of an entraining agent therefor.

10. A process for the transalkylation of magnesium alkyl compounds which comprises the steps of reacting a member selected from the group consisting of lower magnesium dialkyls, and lower alkyl magnesium halides with a higher boron trialkyl at an elevated temperature of up to about 140 C. and at reduced pressure, separating the lower boron trialkyl which is formed from the reaction mixture by distillation in the presence of an entraining agent therefor, said entraining agent having a boiling point which is substantially the same as that of the boron trialkyl formed so that a mixture of the boron trialkyl and entraining agent distills over, separating the boron trialkyl from the entraining agent by reaction with an alkali metal hydride and recovering the transalkylated alkyl magnesium compound from the distillation residue.

11. A process according to claim 10 which comprises supplying the entraining agent from a supply vessel which also contains an alkali metal hydride and introducing the distillate from the distillation comprising entraining agent and lower boron trialkyl into the supply vessel so that the boron trialkyl is continuously removed from the reaction mixture in combined form and continuously recycling the entraining agent.

12. A process according to claim 10 which comprises recovering the transalkylated alkyl magnesium compound from the distillation residue by reaction thereof with carbon dioxide to form the magnesium salt of the corresponding carboxylic acid and reacting said salt with an inorganic acid to thereby produce the free carboxylic acid.

References Cited by the Examiner FOREIGN PATENTS 5/59 Germany.

OTHER REFERENCES CHARLES B. PARKER, Primary Examiner.

TOBIAS E. LEVOW, Examiner. 

1. A PROCESS FOR THE PRODUCTION OF HIGHER CARBOYLIC ACIDS WHICH COMPRISES THE STEPS OF REACTING A MEMBER SELECTED FROM THE GROUP CONSISTING OF LOWER MAGNESIUM DIALKYLS AND LOWER ALKYL MAGNESIUM HALIDES WITH A HIGHER BORON TRIALKYL AT AN ELEVATED TEMPERATURE OF UP TO ABOUT 140*C. AND AT REDUCED PRESSURE, REMOVING THE LOWER BORON TRIALKYL WHICH IS FORMED FROM THE REACTION MIXTURE BY DISTILLATION, TREATING THE DISTILLATION RESIDUE WITH CARBON DIOXIDE TO FORM THE MAGNESIUM SALTS OF THE CORRESPONDING CARBOXYLIC ACIDS, REACTING SAID SALTS WITH ACID TO THEREBY PRODUCE THE FREE CARBOXYLIC ACIDS AND ISOLATING THE RESULTING HIGHER CARBOXYLIC ACIDS THUS PRODUCED.
 6. A PROCESS FOR THE TRANSALKYLATION OF MAGNESIUM ALKYL COMPOUNDS WHICH COMPRISES THE STEPS OF REACTING A MEMBER SELECTED FROM THE GROUP CONSISTING OF LOWR MAGNESIUM DIALKYLS, THE ALKYL RADICALS OF WHICH CONTAIN UP TO 6 CARBON ATOMS AND LOWER ALKYL MAGNESIUM HALIDES, THE ALKYL RADICALS OF WHICH CONTAIN FROM 2 TO 6 CARBON ATOMS, WITH A HIGHER BORON TRIALKYL, AND SEPARATELY RECOVERING THE TRANSALKYLATION PRODUCTS THEREBY PRODUCED. 